「当てる」という意味でお馴染みのhitですが，if a fact hits you, you suddenly realize its importance and feel surprised or shocked（LDOCE）とあるように「〈考えなどが〉〈人に〉思い浮かぶ」という意味があります（『プログレッシブ英和中辞典』小学館）。今回のI don't think it's hit me yet that~は「〜という実感がまだわかない」意味で押さえておこうと思います。（Koyamamoto）
1,200 attend Coming-of-Age ceremony at Tokyo Disneyland
CHIBA, Japan (Kyodo) -- Around 1,200 people turning 20 years old attended a Coming-of-Age ceremony Monday, a national holiday, at Tokyo Disneyland in Urayasu, Chiba Prefecture.
Amid falling snow, Urayasu Mayor Hideki Matsuzaki told the new adults, who were wearing festive dress, "We live in difficult times, but I hope you will change this country in cooperation with your peers."
Takeru Hirota, a 20-year-old college sophomore attending the ceremony, said, "I don't think it's hit me yet that I've come of age...I don't know about my future, but I want to make my own decisions about what I do."